Adjustable oleopneumatic support

ABSTRACT

An adjustable oleopneumatic support, particularly for the height adjustment of the seats of office chairs with central columns, is disclosed. The oleopneumatic element includes a hollow cylindrical body with a packing member realizing an upper and a lower cavity, the respective lower end being rigidly linked to the base of the chair, and a coaxial hollow stem, the head of which is rigidly linked to the seat of the same chair, the hollow coaxial stem being rigidly connected to a piston which defines inside the upper cavity two chambers, an upper and a lower chamber, respectively, both containing fluid; the hollow coaxial stem is provided inside with valvular coaxial actuation means controlling a passage for a hydraulic fluid, the respective outlets being placed above and below the piston, respectively; the lower cavity being able to contain compressed gas.

The present invention concerns an adjustable oleopneumatic support,particularly fit for chairs with central column.

In chairs with a central column an adjustable, gas shock-absorbersupports are commonly used. Such support are generally placed in avertical position inside a guiding telescope cladding, with the endsrespectively, connected to the base and the seat of the chair, andsupport the load applied in a spring fashion.

Such well known gas shock-absorbers are mainly constituted of a pistonwhich, upon application of the load, compresses the gas stored in sideuntil its pressure balances the action of the load; in such condition ofequilibrium, the same pressure acting on the piston, is reached by thegas, thereby supporting the chair and the load applied on it.

The height adjustment of the seat can be effected by opening, withpredisposed valvular means, an inner passage which connects the chamberin which the piston slides to an adjacent compressed gas chamber.

In the absence of a load, the opening of the passage causes the gas toexit from said chamber and, upon expanding the gas lifts the piston;vice versa, by application of a sufficiently heavy load, contemporaneousreverse opening condition occurs which causes the lowering of the pistonand the passage of a further quantity of gas into said chamber with theraising of the pressure in its interior. Such were known gasshock-absorbers, though revealing themselves valid from an exclusivelypratical point of view, are not free from inconveniences, principalamong which is the fact that the gas compressed in the shock absorbersreaches a very high pressure which notoriously results in seriousleakage and escapage of gas and ultimate discharge of the shockabsorber.

In relation to both the stress generated by the high pressure, aiming tokeep within acceptable limits the thickness of the components, of theshock-absorber and to the avoidence of too high springing run,small-diameter tubular elements are generally used however, due to highload points, such small-diameter tubular elements do not possess thenecessary stability and must be normally assembled in combination withcomplementary devices, such as guiding telescopic claddings of biggerdimensions.

An object of the present invention is to eliminate the drawbacks abovementioned in well known types of gas shock-absorbers, by providing anadjustable support in which the height adjustment occurs by fluidshifting from one chamber to the other, without compression, so as tokeep low in every situation the value of the interior pressure andwhich, uses as operating fluid an uncompressable liquid, therebysimplifying appreciably all the problems connected with gas proofing athigh pressure.

Another object of the invention is to achieve an adjustableoleopneumatic element which, for its own peculiar structuralcharacteristics, can support with security and without buckling the fullstress springing from the loads applied on the chair, so as to be usedsingularly, without employing complementary devices.

Still another object of the invention is to provide an oleopneumaticsupport with valvular means of adjustment which, besides being extremelyfunctional and reliable, present an encumbrance extremely reduced, so asto be easily lodged inside the same supporting element, withoutrequiring particular constructive complications.

Yet another object of the invention is to provide an adjustableoleopneumatic support which is easily constructed from elements andmaterials commonly available in commerce, which is rapidly assembled andwhich is economically competitive.

These and other objects, features and advantages of the invention areachieved by an adjustable oleopneumatic support, particularly for chairswith a central column, including a hollow cylindrical body, of with acentral column, including a hollow cylindrical body, of which lower baseis rigidly linkage to the base of the chair, and a coaxial stem, ofwhich head is rigidly linkage to the seat of the same chair, in whichthe stem is fluently, and sealingly coupled with the upper base of saidcylindrical body and with a transversal septum which separates theinterior of said cylindrical body in an upper cavity, developing itselfin correspondence to said upper base, and in a lower cavity developingitself in the opposite side. The stem is rigidly associated to a pistonwhich defines inside the upper cavity two chambers, both containingfluid; the shifting of said piston inside said upper cavity causes,through oil passage way valvular means, the transitory passage of saidfluid from one chamber to the other allowing, for the contrast andaction of a compressed gas present inside of said lower cavity, theheight adjustment of the seat of the chair characterized in that saidoil passageway with valvular means includes a mobile shutter blockslidable in said coaxial stem presenting, in its own lateral surface, inone shift position a first reduced annular area connecting said twoopposed outlet oil passage way means to link the opposed chambers, andin the opposed shifted position interdiction of said oil passage way.

Further characteristics and advantages of the invention will been seenfrom the following description of a preferred embodiment illustrated byway of example in the enclosed drawings, in which:

FIG. 1 is a side view of the oleopneumatic element, in which thecylindrical body is represented in a longitudinal section;

FIG. 2 is a longitudinal section that evidences the valvular means in aclosed position;

FIG. 3 is a longitudinal section that evidences the valvular means in anopened position;

FIG. 4 is a perspective view of a chair with central column.

With reference to the drawings, an adjustable oleopneumatic support,inclusively indicated with reference number 1, includes a hollowcylindrical body 2, opportunely constituted for a first tubular element3 closed, leak proof, in its own lower base, externally tapered, by acap 4.

The cap 4 is fixed, with a first elastic ring 5 and is then equippedwith a first sealing gasket ring 6; in the same way, in other realizableforms; the cap 4 can directly be fixed to the first tubular element 3 bya circumferential welding cord.

To the base opposite to the cap 4, on the first tubular element 3 isconnected a holed stem guiding plate 7, fixed hydraulic seal for exampleby an elasting ring 8, with the interposition of a second sealing gasketring 9.

According to the invention, the inside of the cylindrical body 2 isdivided into two cavities, respectively upper 10 and lower 11, by aholed transversal chamber partition septum 12, which is advantageouslybound or fixed, leak proof, to the first tubular element 3 by a thirdelestic ring 13 and with the interposition of a third sealing gasketring 14.

Coaxially to the cylindrical body 2, the oleopneumatic element 1includes a stem 15, axially sliding through both the stem guiding plate7 and the chamber partitium septum 12, according to couplings renderedleak proof by the presence of seal means, respectively advantageouslyconstituted by sliding gasket oilseal rings 16 in said stem guidingplate 7 and sliding gasket oilseal ring 17-18 in said chamber partitionseptum.

To the stem 15 is rigidly fixed, as for example shown in FIGS. 2 and 3with the use of stopping ring means 19 of sliding gasket oilseal ringmeans 21 (e.g., O-ring), piston 20 slidable in the upper cavity orchamber partition 10 of the cylinder 3.

The piston divides the upper cavity 10 into two chambers, respectivelyupward and downward chamber 22 and 23, of which both contain fluid, forexample hydraulic oil, for which the shifting of the piston 20, andconsequently of the stem 15, is possible only with the opening ofappropriate valvular means provided by holes 40, 41 which allow thefluid to move from one chamber to the other and vice versa.

Advantageously, as evidenced in the drawings 2 and 3, the valvular meansare housed inside the hollow stem 15 advantageouusly realized in tubularform 24 closed in correspondence of its own head 25, externally taperedby a holed cylindrical shutting element 26, fixed by a first elasticstopping ring 27 and, on the opposite side, by a cap 28 externallybulged.

The cap 28, which develops itself towards the inside of the stem 15,with its own stem 29 having a cylindrical end 30, is advantageouslyfixed to the tubular stem 24 by a second elastic stopping ring 31 and isequipped, in the bulged space, of a first sealing ring 32.

According to the invention, the valvular means inside the stem 15,include a shutting block 33, substantially cylindrical, which presents,in its own lateral surface, a reduced upper area 34, placed between anupper edge 35 an a middle edge 36, and a reduced lower area 37, placedbetween the middle edge 36 and a lower edge 38.

All three edges 35, 36 and 38 are equipped with suitable sealingslidable gasket rings 39 sealing said reduced upper area and saidreduced lower area 34,37 in correspondence of respective holes 40,41allowing to pass the oil from the upwards chamber to the downwardschamber and vice versa only if the reduced upper area is placed betweenholes 40, (stem-rod 42-3 pushed down).

More particularly, while the upper edge 35 moves, remaining howeveralways above the first set of holes 40 and the lower edge 38 alwaysbelow the second set of holes 41, the middle edge 36, in its movement,can overpass the second set of holes 41 shifting above and under it.

On one side of the block 33 is connected the stem-rod 42, coaxial to thestem 15, which protrudes with its own end 43 from the head 25; on theopposite side of the block 33 act instead elastic means, advantageouslyconstituted by a spiral spring 44 abutting in correspondent axialbulb-seat protrusion 45.

The spiral sring 44 is compressed between an axial protrusion 45 of theblock 33 and a seat 46 opportunely obtained on the cylindrical end 30 ofthe cap 28.

The spring 44 presses on the block 33 causing the upward movement untilthe stopping plate 47, elastically fixed into a suitable seat present inthe upper portion of the internal stem-rod 42 and efficientlyconstituting a checking element, goes to engage itself, with theinterposition of a rubber ring 48, against the shutting cylindricalelement 26; in this position, the middle edge 36 finds itself betweenthe two sets of holes 40 and 41, while the upper edge 35 and the loweredge 38 find themselves respectively above the first set of holes 40 andbelow the second set of holes 41.

Moreover it must be specified that in the cap 4 is present a threadedhole in which advantageously can be mounted a valve, or a shuttingsealproof screw 49, which allows the filing of the lower cavity 11 withcompressed gas, as for example compressed air; further in correspondenceto the inside face of the cap 4 there is an end-stroke stopper 50, forexample in rubber, which, at the total lowering of the stem 15, engagesitself with the cap 28.

From the foregoing description the functioning of the adjustableoleopneumatic support, according to the invention, appears evident andcan be summarized as follows.

The lower base of cylindrical body 2 and the head 25 of the stem 15 arerespectively connected, exploiting opportunely the taper, to a base 51and to a seat 52 of a chair with central column, as shown simply as anexample in drawing 4.

In absence of action on the upper end 43, the spring 44 maintains thestopping plate 47 engaged against the cylindrical shutting element 26,so that the shutter block 33 finds itself in a position correspondent tothe positioning of its middle edge 36, between the two sets of holes 40and 41; with the valvular means in this position no traversing of oilcan obviously occur between the two chambers 22 and 23 and the stem 15is blocked and able to support eventual loads which are applied to andact on the seat 52 of the chair (FIG. 2).

To modify the length of the adjustable oleopneumatic support and therebyaccomplish the height adjustment of the seat 52 the upper end 43 of theinner stem-bar 42, is pressed down causing compression of the spring 44and moving the shutter block 33 into the position shown in FIG. 3; insuch position the recessed upper area 34 puts into comunication the twosets of holes 40 and 41, determining a circumferential passage thatallows the oil to flow from one to the other of the two upwards anddownwards chambers 22 and 23, as shown by the arrows in the drawing.

If one desires to raise the seat 52, it is sufficient to keep the end 43pressed without applying loads to the chair until the stem lifts itselfto the position desired, pushed by the action exerted on the convexbottom of the cap 28 by the pressure of the gas inside the lower cavity11; if, vice versa, one wishes to lower the seat 42, he mustsimultaneously apply to the chair a light downwards push sufficient towin the modest gas pressure to make the stem 15 go down, inside thelower cavity 11, as much as desired.

Having accomplished the adjustment, the end 43 is released and theshutter block 33 returns into the shutting position, blocking the stem15 at the chosen height.

It is obvious that the presence of the upper edge 35 and the lower edge38 prevent in every situation the flow of the oil outside; particularly,the lower edge 38 keeps the area below the shutter block clear so thatthe lowering of the shutter block 33 will not be hindered by thepresence of oil, the movement of shutter block 33 always will be smoothand the force to be applied to the end 43 always will be of modestintensity.

It has been verified in practice that the application of leads, evenconsiderable, on the chair, is totally transferred from the piston 20 tothe oil, which acts as sole supporting element.

It is moreover evident that the gas which is inside the lower cavity 11,does not suffer in any way from the applied load because it does notbear any supporting function but it is only used to supply the necessarypush to raise the seat during the adjustment; therefore the pressure ofthe gas will be of a modest value, affording the advantages of leakproofness, safety and reliability of the oleopneumatic support.

Moreover, the lower pressures involved allow for the use of acylindrical body 2 of a bigger diameter which associated with theparticular stability of the stem 15, due to the movement through threeguiding elements (holed plate 7, septum 12 and piston 20), allow therealization of supporting elements 2 that just by themselves have thenecessary a stability and lift force to render superfluous the use ofauxiliary supporting elements of stabilizing shells.

The invention so conceived is susceptible of many modifications, allwithin the ambit of the inventive conception; so for example,modifications different from those illustrated herein might be made tothe valvular means and to the leak proof connections between the variouselements. Moreover, various elements illustrated herein might bereplaced by other technically equivalent elements. Nevertheless, suchmodifications an replacements are within the scope and spirit of thepresent invention.

In practice, the materials employed, provided they are compatible withthe contingent use and dimensions, might be according to the demand andthe technical state.

I claim:
 1. An adjustable oleopneumatic support comprising:(a) a hollow,cylindrical body having an interior; (b) a hollow, cylindrical stemcoaxially and sealingly slidable inside said cylindrical body; (c) anannular partition septum mounted transverse to said hollow stem and atan intermediate position of said cylindrical body so that said annularposition septum divides the interior of said cylindrical body into upperand lower cavities; (d) a piston rigidly associated to said cylindricalstem, said piston defining inside said upper cavity an upward chamberand a downward chamber; and (e) valvular actuation means coaxiallyinserted in said cylindrical stem, said valvular actuation meansincluding upward and downward fluid passageway means and a shutter blockslidably inserted inside said cylindrical stem and movable between firstand second positions, said shutter block including a lateral surfacehaving a first reduced annular area so that when said shutter block ismoved to said first position, said first reduced annular area connectssaid upward and downward fluid passageway means and when said shutterblock is moved to said second position, said upward and downward fluidpassageway means are disconnected.
 2. An adjustable oleopneumaticsupport according to claim 1, wherein said shutter block furtherincludes a second reduced annular area adjacent to said first reducedannular area, said first and second reduced annular area being separatedfrom one another by a middle circumferential edge and delimitedexternally by an upper circumferential edge and a lower circumferentialedge, said middle, upper and lower edges coupling themselves fluently,and further including a hydraulic seal sealingly abutting an interiorwall of said cylindrical stem.
 3. An adjustable oleopneumatic supportaccording to claim 2, wherein said upper and middle circumferentialedges are in spaced relationship to one another and comprise said fluidpassageway means.
 4. An adjustable oleopneumatic support according toclaim 1, wherein said cylindrical stem further includes a head.
 5. Anadjustable oleopneumatic support according to claim 4, further includinga coaxial stem-bar connected to said shutter block and substantiallyupwardly protruding from the head of said cylindrical stem, said coaxialstem-bar allowing downward movement of the shutter block which in turnplaces said first reduced annular area into said first position so as toallow interconnection of said upward and downward chambers andconsequent free fluid passage therebetween.
 6. An adjustableoleopneumatic support according to claim 1, further including elasticmeans located under said shutter block at said lower circumferentialedge.
 7. An adjustable oleopneumatic support according to claim 1,wherein said cylindrical body further includes a base and an occludableopening for filling said lower cavity with gas.
 8. An adjustableoleopneumatic support according to claim 7, wherein said lower cavityincludes elastic abutment means to stop downward shifting of saidcylindrical stem.